The objective of this research is to study the physiological aspects of amino acid fermentations by clostridia, particularly those of ornithine fermentation. Much is known about the biochemistry of amino acid fermentations as determined by in vitro investigations, but little information is available concerning the physiological responses of the cells to various amino acids. We expect to evaluate the utilization of various amino acids as sources of energy and carbon in cells of Clostridium sticklandii and Clostridium sporogenes. The general approach will be to investigate molar growth yields and adenylate energy charges in cells in the presence of various amino acids and correlate the findings with viability and growth responses of the cells. We also anticipate studying the interconversion of certain amino acids in the cells and their role in biosynthesis. Finally studies of the regulation of various enzymes involved in amino acid metabolism will be investigated.